The present disclosure is directed broadly to micro-electromechanical systems (MEMS) devices and, more particularly, to rotating devices built using MEMS technology.
MEMS technology borrows heavily from the field of solid state electronics manufacturing. Using the same or similar steps used by electronics manufacturers, gears with teeth measured in the tens of microns have been fabricated. The ability to fabricate gears and other moving parts on such small scales has led to the creation of micro-engines and micro-turbines.
The invention disclosed in U.S. Pat. No. 5,932,940 provides a micro-gas turbine engine and associated micro-componentry. The engine components, including, e.g., a compressor, a diffuser having diffuser vanes, a combustion chamber, turbine guide vanes, and a turbine are each manufactured by, e.g., micro-fabrication techniques, of a structural material common to all of the elements, e.g., a micro-electronic material such as silicon or silicon carbide. Vapor deposition techniques, as well as bulk wafer etching techniques, can be employed to produce the engine. The engine includes a rotor having a shaft with a substantially untapered compressor disk on a first end, defining a centrifugal compressor, and a substantially untapered turbine disk on the opposite end, defining a radial inflow turbine. The rotor is preferably formed of a material characterized by a strength-to-density ratio that enables a rotor speed of at least about 500,000 rotations per minute. An annular, axial-flow combustion chamber is provided that is located axially between the compressor and turbine disks and that has a ratio of annular height to axial length of at least about 0.5. The micro-gas turbine engine can be configured with an integral micro-generator as a source of electrical power, and can be employed for a wide range of power, propulsion, and thermodynamic cycle applications.
Problems associated with such small devices include controlling the supply of fuel and controlling parameters such as temperature and pressure needed to insure proper combustion, among others.